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The starting point for many fire safety regulations, like NFPA 130, is often paying homage to local building codes. (Section 5.1.2. Relationship with local codes, defines the code to be supplemental to the local codes). These prescriptive codes emphasize the importance of following well-established practices for fire safety and life safety. Additionally, codes like NFPA 130 often reference the Life Safety Code (NFPA 101) or local codes to ensure a consistent safety baseline.
While prescriptive codes provide a strong foundation, they may not always account for the unique characteristics of a specific building. This is where Fire Engineering (FE) strategies come in. These strategies leverage scientific principles and advanced modeling to design fire safety strategies and systems tailored to a building's specific layout, occupancy, and potential fire hazards. This approach is particularly valuable for complex structures like transit stations, where a line-wide strategy along with station-specific solutions might be necessary.
However, it's important to consider that even with a fire engineering strategy, adhering to local building codes can still be crucial. For instance, in transit stations, while passenger areas might benefit from the flexibility of fire engineering, plant rooms and back-of-house spaces might still require adherence to prescriptive codes to ensure baseline safety measures are in place. This is what many countries follows.
I am not sure I particularly accept the last basis, for the BOH areas, why? Station are generally design to a higher standards - both front of house and back of house. Following prescriptive code on top of fire engineering standards only makes transit system more expensive, harder to manage; with limited advantage.
KEY TAKE AWAY FROM NFPA 130, ETC.
KEY TAKE AWAY FROM NFPA 130, ETC.
As NFPA 130 forms the basis for many, if not most of the life safety code for the transit systems globally. Some of which has been extracted for reference below, with commentary.
Fig. Graphical illustration of Platform Egress requirement as per NFPA 130
Fig. Section illustrating Platform Egress standards
SOME ADDITIONAL NOTES
SOME ADDITIONAL NOTES
The 4 min egress time is also relevant for other areas and fire there. Say passages, etc.
The 4 min requirements only vary to 4.5min in the Hong Kong MTR systems. Most follow this 4 min basis, including China
The 6 min criteria allow for certain passages at upper level to be grouped into the platform compartment, after which the extended egress time is possible, provided the fire engineering basis is provided. The 4 min platform evacuation time still applies.
These requirements only references some of the station planner's basis. MEP requirements have been ignored. Nevertheless, some of this has been captured in the following chapters.
WHAT ARE DESIGN STANDARDS?
WHAT ARE DESIGN STANDARDS?
For most building typologies, there are various standards and specification that can be followed.
For example, Hotels will have their local building codes, different operators such as Hyatt, Sheraton, etc, will enhance this with their own design standards and specifications, adapted to sync with the local building code. The same would be the case for corporate office designs, different developers will have their own enhanced version of grade types, specification, etc. If you ensure your building with companies such as FM Global, then you may need to enhance your building standards and specifications.
However, for transit stations, they are left on their own. Hence many systems such as the LUL (London), MTR/MRT (Hong Kong/Singapore). MTA (New York), etc. have created their own design standards and specification that inherently appends life safety codes, underpins life safety and operational readiness. Nevertheless, one can see in-house design standards in metro systems, which are never reviewed or adapted with time, or events. Which is perhaps not the right thing to do, as we need to constantly adapt with time, etc.
So why does the Hong Kong system have a different standard that is much more forgiving? The reason is that when the system was designed between late 1960-1970, the overall capacity required was so high, that empirical studies were carried out to provide that escalator, stairs, safety evacuation time in the platforms, etc. were all defined, and standards sets. It is my view that from a life safety perspective these changes have very limited impact in the Hong Kong system, in fact the MEP systems in the HK MTR are so well developed and elaborate, that suppression, mitigation and management systems trump ones seen in any other system in the world.
As a parting sentence, please review the below studies, which compares the empirical basis of NFPA 130 platform egress time of 4 minutes and the 6 minutes egress time to a point of safety, plus simulation exercise taken. Implying that a binary view on life safety is not advised.
Comparing NFPA 130, SFPE, and Pathfinder
https://www.mlit.go.jp/english/2006/h_railway_bureau/Laws_concerning/15.pdf
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